Nickel-base braze material and braze repair method

Abstract

A braze material and method for repairing an article, such as a gas turbine engine combustor liner formed from a nickel-base or cobalt-base superalloy. The braze material is composed of a nickel-base braze alloy that is preferably in powder form and may be dispersed in a suitable vehicle to yield a slurry, putty or solid tape. The braze alloy is formulated to be capable of withstanding the high temperature operating environment of a combustor liner, and to have a melting temperature below the grain growth or incipient melting temperature of the superalloy to be repaired. A preferred braze alloy is formed by combining at least two nickel-base powders. A suitable composition for the braze alloy is, in weight percent, about 10 to about 19 chromium, about 3 to about 10.5 cobalt, about 1.75 to about 4.9 titanium, about 0.75 to about 3.4 aluminum, about 1.25 to about 4.1 tungsten, about 1.25 to about 4.1 molybdenum, about 0.025 to about 0.225 carbon, about 0.005 to about 0.15 zirconium, about 0.50 to about 2.6 boron, up to 1.5 iron, with the balance being nickel and incidental impurities.

What is claimed is:  
     
       1. A nickel-base braze material for repairing nickel-base and cobalt-base superalloy articles (10), the braze material comprising first and second nickel-base powders, the first nickel-base powder consisting essentially of in weight percent: 10 to 18 chromium, 6 to 14 cobalt, 3.5 to 6.5 titanium, 1.5 to 4.5 aluminum, 2.5 to 5.5 tungsten, 2.5 to 5.5 molybdenum, 0.05 to 0.30 carbon, 0.01 to 0.20 zirconium, 0.001 to 0.2 boron, wherein the combination of tungsten and molybdenum is at least 5.0, the balance being nickel and incidental impurities; the second nickel-base powder consisting of, in weight percent: 10.0 to 20.0 chromium, 2.0 to 5.0 boron, up to 3.0 iron, the balance being nickel and incidental impurities, wherein the weight ratio of the first nickel-base powder to the second nickel-base powder in the braze material is about 50:50 to 75:25. 
     
     
       2. A nickel-base braze material according to  claim 1 , further comprising a binder. 
     
     
       3. A nickel-base braze material according to  claim 2 , wherein the nickel-base braze material is in a form selected from the group consisting of a slurry, tape or putty. 
     
     
       4. A nickel-base braze material according to  claim 1 , wherein the first and second nickel-base powders are sintered together such that the nickel-base braze material is in the form of a sintered preform. 
     
     
       5. A nickel-base braze material according to  claim 1 , wherein the first nickel-base powder consists of, in weight percent: 13.7 to 14.3 chromium, 9.0 to 10.0 cobalt, 4.80 to 5.20 titanium, 2.80 to 3.20 aluminum, 3.70 to 4.30 tungsten, 3.70 to 4.30 molybdenum, 0.15 to 0.19 carbon, 0.03 to 0.10 zirconium, 0.01 to 0.02 boron, wherein the combination of tungsten and molybdenum is at least 7.7, the balance being nickel and incidental impurities. 
     
     
       6. A nickel-base braze material according to  claim 1 , wherein the second nickel-base powder consists of, in weight percent: 13.00 to 17.00 chromium, 3.00 to 4.00 boron, up to 1.5 iron, the balance being nickel and incidental impurities. 
     
     
       7. A nickel-base braze material according to  claim 1 , wherein the weight ratio of the first nickel-base powder to the second nickel-base powder in the braze material is about 65:35. 
     
     
       8. A nickel-base braze material according to  claim 1 , wherein the first and second nickel-base powders are combined within the nickel-base braze material to yield a nickel-base braze alloy that consists essentially of, in weight percent, about 10 to about 19 chromium, about 3 to about 10.5 cobalt, about 1.75 to about 4.9 titanium, about 0.75 to about 3.4 aluminum, about 1.25 to about 4.1 tungsten, about 1.25 to about 4.1 molybdenum, about 0.025 to about 0.225 carbon, about 0.005 to about 0.15 zirconium, about 0.50 to about 2.6 boron, up to 1.5iron, with the balance being nickel and incidental impurities. 
     
     
       9. A superalloy article having a crack filled with the braze material recited in  claim 1 . 
     
     
       10. A superalloy article according to  claim 9 , wherein the article is formed of a superalloy whose nominal composition is, in weight percent, either: 
       about 22.4 chromium, about 19.0 cobalt, about 3.7 titanium, about 1.9 aluminum, about 2.0 tungsten, about 1.4 tantalum, about 1.0 niobium, about 0.10 zirconium, about 0.15 carbon and about 0.009 boron, the balance nickel and incidental impurities; or  
       about 22.5 chromium, about 14.0 cobalt, about 2.3 titanium, about 1.2 aluminum, about 2.0 tungsten, about 0.8 columbium, and about 1.0 tantalum, the balance nickel and incidental impurities.  
     
     
       11. A superalloy article according to  claim 9 , wherein the article is a combustor liner of a gas turbine engine. 
     
     
       12. A superalloy article according to  claim 9 , wherein the combustor liner is formed of a nickel-base or cobalt-base superalloy, the combustor liner having transpiration cooling holes and a crack through at least one of the holes, the crack being filled with a nickel-base braze alloy formed by the nickel-base braze material, the nickel-base braze alloy consisting essentially of, in weight percent, about 10 to about 19 chromium, about 3 to about 10.5 cobalt, about 1.75 to about 4.9 titanium, about 0.75 to about 3.4 aluminum, about 1.25 to about 4.1 tungsten, about 1.25 to about 4.1 molybdenum, about 0.025 to about 0.225 carbon, about 0.005 to about 0.15 zirconium, about 0.50 to about 2.6 boron, up to 1.5 iron, with the balance being nickel and incidental impurities. 
     
     
       13. A combustor liner according to  claim 12 , wherein the nickel-base braze alloy consists essentially of, in weight percent, about 13.4 to about 15.3 chromium, about 5.8 to about 6.5 cobalt, about 3.1 to about 3.4 titanium, about 1.8 to about 2.1 aluminum, about 2.4 to about 2.8 tungsten, about 2.4 to about 2.8 molybdenum, about 0.10 to about 0.13 carbon, about 0.02 to about 0.07 zirconium, about 1.0 to about 1.4 boron, up to 1.0 iron, with the balance being.nickel and incidental impurities.